I'm not sure the system (re-)suggested by Sigi would require to force you to take your short rest before your long rest.
Couldn't the game skip the middle cycle to go from morning to night if the player click the long rest button ?
And who stated that long rest is only during the night ? I'm not sure how it works/will work but does the camp dialogs/cutscenes absolutely need to be at night ? (For technical reasons ? Story reasons ? Idk).
Short rest could maybe pass 1 cycle while long rest would go 2 cycles further. I'm not sure there's engine limitation for D/N cycle... But I'm close to sure that devs that want a D/N cycle in their game can be creative. It shouldn't be that hard, everyone has a D/N cycle, even games far less polished than BG3.
Night instance for quests would really suck. It looks cheaper than anything else to me... Especially if the night quests arrive after 50 hours without night gameplay.